1. Technical Field
The present invention relates to a method and an apparatus for image inspection, and particularly to a method and an apparatus for image inspection for quickly performing a check of a minute defect or foreign matter on an identified image (an image to be identified, an image to be inspected, an image to be checked), a comparison, collation and check between the identified image and a reference image, or the like.
2. Background Art
As conventional digital image processing methods of image defect extraction, following methods are enumerated.
(1) A method of performing the convolution of Fourier transformed (FFT) images of a reference image and a checked image and the inverse Fourier transform (FFT) thereof for a check of a defective image of a minute lack, projection or the like in a conventional digital image processing method (see non-patent document 1 with respect to a position correcting method, and see non-patent document 2 with respect to a calculation time).
(2) In a conventional digital image processing method, in order to identify a very minute defect in a large size image, a comparison is made in an image recorded on pixels of an electronic camera (see non-patent document 3).
In addition, as the related art, there are a Fourier transformed image comparison method (see non-patent document 4) as an optical analog identification method, and a large visual field acquisition method of a sharpened image (see non-patent document 5).
Besides, conventionally, there is a method in which a check image signal and a reference image signal are Fourier transformed, and a complex conjugate of phase components of the Fourier transform of the checked image signal and the reference image signal is multiplied to obtain a combined image signal, and further, the obtained combined image signal is inverse Fourier transformed, so that a defect of a shadow mask is detected (see patent document 1).
Patent document 1: JP-A-2000-215803
Non-patent document 1: edited by Hideyuki Tamura, “Computer Image Processing: Application Practice Part 1” Souken Shuppan, p 147
Non-patent document 2: edited and written by Satoshi Kawada, Shigeo Minami, “Image Data Processing for Scientific Measurement” CQ Publishing Co., Ltd., p 126
Non-patent document 3: written by Junichiro Toriwaki, edited by Shigeo Tsujii, “Digital Image Processing for Image Comprehension [1]” Shokodo Co., Ltd., p 12
Non-patent document 4: Nobuyuki Akiyama “Technology Inspecting Foreign Matter” O plus E (2001-5) (measurement and technology for inspecting in semiconductor industry) p 562
Non-patent document 5: The Japan Society for Precision Engineering, edited by the image applied technology expert committee, “Image Processing Applied System”, Tokyo Denki University Press, p 145